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hw/ide/piix: Add some documentation to pci_piix3_xen_ide_unplug()

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The comment is based on commit message
ae4d2eb273 'xen-platform: add missing disk
unplug option'. Since it seems to describe design decisions and
limitations that still apply it seems worth having.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Message-Id: <20220513180957.90514-3-shentey@gmail.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
This commit is contained in:
Bernhard Beschow 2022-05-13 20:09:56 +02:00 committed by Anthony PERARD
parent 7851b21a81
commit 3690241746
1 changed files with 11 additions and 0 deletions
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11
hw/ide/piix.c
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@ -173,6 +173,17 @@ static void pci_piix_ide_realize(PCIDevice *dev, Error **errp)
}
}
/*
* The Xen HVM unplug protocol [1] specifies a mechanism to allow guests to
* request unplug of 'aux' disks (which is stated to mean all IDE disks,
* except the primary master).
*
* NOTE: The semantics of what happens if unplug of all disks and 'aux' disks
* is simultaneously requested is not clear. The implementation assumes
* that an 'all' request overrides an 'aux' request.
*
* [1] https://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=docs/misc/hvm-emulated-unplug.pandoc
*/
int pci_piix3_xen_ide_unplug(DeviceState *dev, bool aux)
{
PCIIDEState *pci_ide;